Minimization of operating time gap between primary relays at near and far ends in overcurrent relay coordination

In bidirectional fault feed distribution lines, the fault should be cleared from both the fault feeding sources ends simultaneously, so that impact of faults currents on the exiting over current relay coordination will be minimum. In existing over current relay coordination algorithms, it is observed that operating time gaps between primaries over current relays at near end and far end of faulted line are quite enough. This time gaps may redistribute the fault currents in the power networks which leads to cascading type of over current relay miscoordination in a properly coordinated power network. In this paper, the over current relay coordination problem formulation is modified in such a way to minimize the operating time gap between the primary over current relays at near and far ends with in a desired time margin such that the chance of redistribution of fault currents in the distribution network is eliminated. The proposed modified over current relay coordination algorithm is implemented in 8 bus test distribution system.